Waveguide and head-mounted display device

Abstract

A waveguide and a head-mounted display device are provided. The waveguide is used for transmitting an image beam. The waveguide includes a plate, at least one coupling-in prism, and microstructures. The plate has a first surface and a second surface. The image beam enters the plate through the first surface. The coupling-in prism is located on the second surface. The coupling-in prism has a first inclined surface, and the image beam is reflected by the first inclined surface and then transmitted in the plate. The microstructures are located on the second surface. Each microstructure has a second inclined surface. The image beam exits from the first surface after being reflected by the second inclined surface. A difference between refractive indices of the coupling-in prism and the microstructures is less than 0.05.

What is claimed is: 
     
         1 . A waveguide configured to transmit an image beam, wherein the waveguide comprises a plate, at least one coupling-in prism and a plurality of microstructures, wherein:
 the plate has a first surface and a second surface, and the image beam enters the plate through the first surface;   the at least one coupling-in prism is located on the second surface, wherein the coupling-in prism has a first inclined surface, and the image beam is reflected by the first inclined surface and then transmitted in the plate; and   the plurality of microstructures are located on the second surface, wherein each of the plurality of microstructures has a second inclined surface, the image beam is reflected by the second inclined surface and then exits from the first surface of the plate, and a difference between a refractive index of the coupling-in prism and a refractive index of the plurality of microstructures is less than 0.05.   
     
     
         2 . The waveguide of  claim 1 , wherein a refractive index of the plate is greater than the refractive index of the coupling-in prism and the refractive index of the plurality of microstructures. 
     
     
         3 . The waveguide of  claim 1 , wherein the first inclined surface of the coupling-in prism is inclined relative to the second surface to form a first included angle, the second inclined surface of the plurality of microstructures is inclined relative to the second surface to form a second included angle, and the first included angle and the second included angle are equal or the first included angle and the second included angle have a difference less than 3 degrees. 
     
     
         4 . The waveguide of  claim 1 , wherein the each of the plurality of microstructures has a reflective layer, the reflective layer is located on the second inclined surface, and the reflective layer is a specular reflective layer. 
     
     
         5 . The waveguide of  claim 1  further comprising:
 a compensation layer, covering the second inclined surface of the plurality of microstructures, wherein the compensation layer forms a first plane on a side away from the second inclined surface of the plurality of microstructures, and the first plane is parallel to the first surface and the second surface. 
 
     
     
         6 . The waveguide of  claim 5 , wherein a height of the plurality of microstructures exceeds one-tenth of a height of the plate, the compensation layer covers an entire area of the second surface of the plate, and in an area on the second surface of the plate where the coupling-in prism is provided, the compensation layer is located between the coupling-in prism and the plate. 
     
     
         7 . The waveguide of  claim 5 , wherein a height of the plurality of microstructures is less than one-tenth of a height of the plate, the compensation layer covers an area on the second surface of the plate where the plurality of microstructures are provided or an entire area of the second surface of the plate, and in an area on the second surface of the plate where the coupling-in prism is provided, the compensation layer is located between the coupling-in prism and the plate. 
     
     
         8 . The waveguide of  claim 5 , wherein the compensation layer is made of the same material as the plate. 
     
     
         9 . The waveguide of  claim 5 , wherein the each of the plurality of microstructures has a reflective layer, the reflective layer is located on the second inclined surface, and the reflective layer is a specular reflective layer or a partially reflective layer. 
     
     
         10 . The waveguide of  claim 1 , wherein the plurality of microstructures form a micromirror array. 
     
     
         11 . A head-mounted display device configured to be disposed in front of at least one eye of a user, wherein the head-mounted display device comprises a display unit and a waveguide, wherein:
 the display unit is configured to provide an image beam; and   the waveguide is configured to transmit the image beam to the at least one eye of the user, and the waveguide comprises a plate, at least one coupling-in prism, and a plurality of microstructures, wherein:
 the plate has a first surface and a second surface, and the image beam enters the plate through the first surface; 
 the at least one coupling-in prism is located on the second surface, wherein the coupling-in prism has a first inclined surface, and the image beam is reflected by the first inclined surface and then transmitted in the plate; and 
 the plurality of microstructures are located on the second surface, wherein each of the plurality of microstructures has a second inclined surface, the image beam is reflected by the second inclined surface and then exits from the first surface of the plate, and a difference between a refractive index of the coupling-in prism and a refractive index of the plurality of microstructures is less than 0.05. 
   
     
     
         12 . The head-mounted display device of  claim 11 , wherein a refractive index of the plate is greater than the refractive index of the coupling-in prism and the refractive index of the plurality of microstructures. 
     
     
         13 . The head-mounted display device of  claim 11 , wherein the first inclined surface of the coupling-in prism is inclined relative to the second surface to form a first included angle, the second inclined surface of the plurality of microstructures is inclined relative to the second surface to form a second included angle, and the first included angle and the second included angle are equal or the first included angle and the second included angle have a difference less than 3 degrees. 
     
     
         14 . The head-mounted display device of  claim 11 , wherein each of the plurality of microstructures has a reflective layer, the reflective layer is located on the second inclined surface, and the reflective layer is a specular reflective layer. 
     
     
         15 . The head-mounted display device of  claim 11 , wherein the waveguide further comprises:
 a compensation layer, covering the second inclined surface of the plurality of microstructures, wherein the compensation layer forms a first plane on a side away from the second inclined surface of the plurality of microstructures, and the first plane is parallel to the first surface and the second surface.   
     
     
         16 . The head-mounted display device of  claim 15 , wherein the compensation layer is made of the same material as the plate. 
     
     
         17 . The head-mounted display device of  claim 15 , wherein a height of the plurality of microstructures exceeds one-tenth of a height of the plate, the compensation layer covers an entire area of the second surface of the plate, and in an area on the second surface of the plate where the coupling-in prism is provided, the compensation layer is located between the coupling-in prism and the plate. 
     
     
         18 . The head-mounted display device of  claim 15 , wherein a height of the plurality of microstructures is less than one-tenth of a height of the plate, the compensation layer covers an area on the second surface of the plate where the plurality of microstructures are provided or an entire area of the second surface of the plate, and in an area on the second surface of the plate where the coupling-in prism is provided, the compensation layer is located between the coupling-in prism and the plate. 
     
     
         19 . The head-mounted display device of  claim 15 , wherein the each of the plurality of microstructures has a reflective layer, the reflective layer is located on the second inclined surface, and the reflective layer is a specular reflective layer or a partially reflective layer. 
     
     
         20 . The head-mounted display device of  claim 11 , wherein the plurality of microstructures form a micromirror array.